The letter "U" can signify making a 'u-turn' to go back to something you abandoned. It can embody the idea of 'you' in a cryptic form. Since U-boats travel underwater and UFO's are things that cannot be validated, there may be something unusual you are exploring as an idea that can lead you to unify or balance all the sides of you. This letter can suggest that you might celebrate the quirky things that make you who you are.